Ozone Layer Depletion (Part 1)

Outline of Presentation
 What is the Ozone layer?
 How is ozone created and
destroyed?
 What is the Ozone hole?
 What are the causes of Ozone
Depletion?
Outline of Presentation
 What are Ozone Depleting Substances?
 Effects of the depleting Ozone to humanity and all
living things.
 Impacts of the Ozone Layer depletion to the
Earth.
 How can the Ozone layer be saved?
The Ozone Layer is a thin,
fragile shield that envelops the
entire earth which efficiently
and effectively filters and
screens almost all of the
harmful ultraviolet rays.
Ozone is a gas
that is naturally
present in the
atmosphere.
It is a molecule
made up of
three oxygen
atoms.
air molecules
It’s chemical
symbol is O3.
 Earth’s atmosphere is divided into four layers
with different elevation and temperature
profile:
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
THE GOOD AND BAD OZONE
The Solar Radiation
 The
Earth’s atmosphere is exposed to
radiation from the sun. Energy is transferred
from the sun to the earth in the form of
electromagnetic
energy.
Electromagnetic
energy can be divided into spectrum, in which
protons that transfer energy have both a
wavelength and energy level.
 This radiation includes ultraviolet, visible
and infrared radiations.
There are three
categories of UV:
 UV-A: Most UV-A is able to reach the
earth’s surface.
 UV-B: 90% of UV-B is blocked off by the
ozone layer.
 UV-C: 100% of UV-C is blocked off by the
ozone layer.
HOW OZONE IS CREATED IN THE STRATOSPHERE
How ozone is naturally destroyed in the Stratosphere
UV radiation strikes ozone
molecule…
… releasing one
oxygen atom
O
O
O
O
O
O
What is the
 The depletion or the
loss of the blocking
effect of the ozone layer
against ultraviolet rays
is what we call the
OZONE HOLE.
The Ozone Depletion
 Degradation of the Ozone Layer.
 When even a small amount of ozone
layer is lost, more ultraviolet light from
the sun can reach and destroy the Earth.
 Caused by the chemical reaction
involving chlorine and bromine which
are also called Ozone Depleting
Substances (ODS).
OZONE DEPLETING SUBSTANCES (ODS) AND
THEIR USES
CHLOROFLUOROCARBONS or CFCs
HALONS
• Simple chemicals containing chlorine, • Contain at least one bromine
atom
fluorine and carbon.
• CFCs are used in refrigerators, air- • Halons are primarily used in fire
conditioners, spray cans, solvents, extinguishers
foams, other application.
OZONE DEPLETING SUBSTANCES (ODS) AND
THEIR USES
 CARBON TETRACHLORIDE and METHYL CHLOROFORM are used as
solvents.
 HYDROBROMOFLUOROCARBONS
extinguishers.
(HBFCs)
 HYDROCHLOROFLUOROCARBONS (HCFCs)
first major CFC replacement .
are
used
in
fire
were developed as the
OZONE DEPLETING SUBSTANCES (ODS) AND
THEIR USES
• METHYL BROMIDE (CH3Br) is used as a fumigant and in
quarantine treatment.